The "dot" here represents a pause. If the pause was not there, then the last consonent of the cmevla would/may run into the next word. For example: "[la martin. a'o citka lo plise]" would become "[la marti na'o citka lo plise]". Or: "[la bab. ractu]" would be "[la ba bractu].

Plus there's the other, totally impractical, reason: That it makes our language even weirder looking! We've already got abundant use of X, weird word shapes, lots of apostrophes. So we take it to the next level with a bunch of periods and even COMMAS. Oh yeah baby! If you are looking for an alien looking language for a comic book, have we got your thing! Klingon's uppercasing, oh yeah sO LeEt DudEZ. Come on we're where it's at.